Electric cutout



July 7, 1942. F. l.. HITCHCOCK 2,289,305

ELECTRIC GUT-OUT VFiled Aug. 3, 1940 L MHH 36 H4 im ATTORNEYJ Patented July 7, 1942 UNITED STATES PATENT OFFICE ELECTRIC CUTOUT Forrest L. Hitchcock, Indianapolis, Ind.

Applicatidrn August 3, 1940, Serial No. 350,671

7 Claims.

The object of my invention is to provide a substitute for a standard electrical fuse of the plug type of such character that, when inserted in a standard receptacle, its mechanism may be manipulated to establish a circuit therethrough which, when subjected to a predetermined load, will automatically operate to disrupt the circuit, at the same time giving a visible indication of such disruption, and which will be of such character that, in the absence of such predetermined load, it may be manually reset to again establish the circuit but, when manipulated in the presence of such predetermined load, it may not be so manipulated as to re-establish the circuit.

The accompanying drawing illustrates an embodiment of my invention.

Fig. 1 is a top plan, full size;

Fig. 2 an axial section, on a larger scale, on line 2--2 of Fig. 1 with the parts in circuit closing position under normal load conditions; and

Fig. 3 is an enlarged section on line 2 2 of Fig. 1 under no load conditions.

In the drawing I) indicates a main shell of insulating material provided with an internal longitudinal keyway II and with an external threaded portion I2 at one end to receive the threaded metal cup terminal I3. This cup is of usual and wel] known form and is sized and proportioned to be received in an ordinary screw I 211g socket of a terminal block. Interposed between the inturned flange of cup I3 and the adjacent end of body I5 is an insulating plate 14 axially perforated at I5. Laid upon the inner face of plate I4 is a conductor disc I6 axially perforated to receive the inner end of the terminal pin I1, the ensmalled inner end of which is projected through perforation I5 and attached to disc I5. Sleeved within body IU is a conductive bridging ring I8 provided at one side with a key I9 which is slidable within the keyway II and which serves to prevent rotation of ring I8. Within ring I 8 is a considerably smaller actuator and retainer ring I9 and between these two rings is interposed a thermostatically responsive bi-metallic coil 20, the inner end of which is anchored to ring I9 and its outer end anchored on ring I8. The upper end of ring I9 is upwardly and inwardly beveled, as indicated at 2|, and at diametrically opposite points this upper edge is notched to form downwardly and inwardly inclined surfaces 22. At other diametrically opposite points, conveniently 90 degrees from surfaces 22, the upper edge of ring I9 is notched to form inwardly and downwardly inclined surfaces 23.

Anchored to ring I9, above the anchorage of the thermostatic element 20, is one end of a helical spring conductor 24 which normally lies in a plane near the upper end of body I3, the outer end of this spring being carried downwardly within an exterior longitudinal groove in the outer face of body I Il to a point of attachment with the terminal cup I3.

Sleeved within ring I9 is an operating plunger 25 of insulating material and provided at its lower end with a head 25 which limits movement of the plunger relative to ring I9 in one direction. Plunger 25 is provided with an axial bore 26 from its lower end upwardly for a major portion of its length and at diametrically opposite points is slotted longitudinally at 21, 2'I. Within the bore 26 of the plunger 25 is slidably mounted a pair of spring catches 28 engaged by a spring 29 within the bore 26, said spring, at its lower end, abutting the upper end of a plunger 3D of insulating material, the lower end of this plunger resting upon terminal I'I.

Plunger 25 is longitudinally grooved at diametrically opposite sides, preferably in a plane 90 degrees from the plane of slots 21, as indicated at 3|, 3|.

Arranged in the upper end of the bore of body I0 above the helical spring 2:1 is a plate 35 axially bored to receive plunger 25 and provided with diametrically opposite depending spring catches 36, 36, the major portions of the lengths of which are nested in the grooves 3|, 3l and the lower ends of which lie at all times within tube I9. The plate 35 is thus splined to plunger 25 so that there may be no relative rotation between these two parts. Plate 35, at one point, is provided with an outwardly projecting finger 35 which may be caused to lie in any one of a series of notches 38 in the upper end of shell I0 so that the angular relationship between plunger 25 and tube I9 under normal temperature conditions may be adjusted if desired. Overlying plate 35 is a ring 39 of insulating material axially bored for the passage of the upper end of plunger 25.

A cap cup 40 is sleeved over ring 39 onto body i0 and secured in place against normal accidental removal thereby holding the various parts in assembled relationship.

Plunger 25 is normally urged upwardly to its uppermost projected position by spring 29. When in this position, under normal temperature conditions, catches 28 overlie the beveled upper edge of ring I9 so that downward pressure upon plunger 25 will serve to drive ring I9 downwardly against the resistance of the helical spring 24 carrying with it the contact ring I8 and thermostatic element 2i) until contact ring I8 engages the contact plate I6 at which time spring ngers 36 will fly out to override the upper end of ring I9, as shown in Fig. 2.

Under normal electrical-load conditions neither of the pairs of catches 28-28 and 36-36 will register with surfaces 22 and 23, respectively, but under excessive electrical-load, ring I9 will be rotated by the thermostatic element beneath catches 36-36 until registry of surfaces 23 with catches 36 and surfaces 22 with catches 28 is attained, whereupon the group I9, 20 I8 and the plunger with its associated parts will be returned to circuit breaking position. So long as the thermostatic element remains abnormally heated, notches 22 of tube I9 will remain in registry with catches 28 and therefore the operator may not return ring I8 to circuit making position until the thermostatic element 20 has sufficiently cooled and consequently the operator will not be able to re-establish a circuit in case there is an undesirable short somewhere in the circuit. If the operator should wait until the thermostatic element 20 has cooled so as to swing the notches of ring I9 out of registry with their respective catches and then again press plunger 25 inwardly and the excessive load conditions continue in the circuit, ring I9 will be rotated nevertheless to bring its notches into registry with the catches and the parts will be automatically returned to circuit breaking position even though the operator persists in exerting pressure upon the plunger.

It will be noted that when the parts are in circuit making position the plunger 25 is in its least exposed position and that when the circuit has been broken as a result of thermostatic reaction, the plunger 25 is returned to its most exposed position thereby indicating a circuitbreak relationship of the parts.

If desired, the coil 24 may be bimetallic and set in opposition to coil 20, so as to compensate ordinary variations of room temperatures.

In the embodiment illustrated, the contacting ring I8 comes into contact with terminal I6 slightly before plunger 25 has been fully depressed, owing to the resilience of element 20. If the operator should retain pressure on plunger 25 and if there be an excessive electrical load, element 20 will heat and will turn ring I9 so as to register the notches with the catches and thus permit spring 24 to return the unit I8-20-I9 to circuit-break position.

I prefer to notch the lower end of contact ring I8, as indicated at I8', so as to form three defined contact areas for engagement with the plate I6. By so notching ring I8 said ring will be more definitely and accurately seated upon plate I6 so as to insure adequate electrical contact between ring I8 and plate I5 even though one or more of the contact legs thus formed becomes distorted by reason of sparking.

I claim as my invention:

1. A thermally responsive circuit controller, comprising a tubular main body provided at one end with two electrically-separated terminals arranged to be coactive with the electrically-separated terminals of a standard terminal block, a contact element splined in said main body and movable into and out of contact with one of said terminals and in electrical contact with the other of said terminals, a spring normally biasing said contact element away from contacting position, an actuator ring mounted within the main body and connected with said contact element to partake of its movements toward and from its companion terminal, a thermally-responsive conductor arranged to partake of the electrical load imposed upon said contact element and connected to said actuator ring to angularly adjust it in accordance with the applied electrical load, an accessible actuator means for normally moving said actuator to projected position, a one-way catch interposed between said accessible actuator and the actuator ring, and a catch interposed between the main body and the actuator ring to retain the contact element in contacting position, said two catches and the actuator ring being so relatively formed that the catches will be eiective in one angular position of the ring and ineffective in a different angular position of the ring.

2. In an electrical switch, a contact plate and a contact ring, one movable relative to the other axially of the ring to make or break electrical Contact, the contacting end of said ring being notched to form only three axially projecting circumferentially separated non-yielding contacting legs.

3. A thermally responsive circuit controller comprising a main body provided at one end with two electrically-separated contact elementsma contact ring electrically connected with one of said Contact elements and axially shiftable to and from engagement with the other of said contact elements, a helical element anchored at one end to said shiftable contact element and thermally responsive to shift its other end circumferentially relative to said shiftable contact element, a latch carried by the main body, a latch-engageable member carried by the said other end of the thermally-responsive element and Variably positioned thereby circumferentially relative to said latch, said latch and latch-engageable element being so formed that, in 4one angular position of the latch-engageable element, the latch cannot restrain it from axial movement, and a manually-associable operating element axially shiftable in the main body and engageable with sai-d latch-engageable element to shift it and said contact ring to position where said latch may engage and retain said latch-engageable element in projected position.

4. A thermally responsive circuit controller comprising a main body provided at one end with two electrically-separated contact elements, a tiltable contact ring electrically connected with one of said contact elements and axially shiftable to and from engagement with the other of said contact elements and having three circumferentially spaced contact feet, a helical element anchored at one end to said shiftable contact element and thermally responsive to shift its other end circumferentially relative to said shiftable contact element, a latch carried by the main body, a latch-engageable member carried by the said other en-d of the thermally-responsive element and variably positioned thereby circumferentially relative to said latch, said latch and latch-engageable element being so formed that, in one angular position of the latch-engageable element, the latch cannot restrain it from axial movement, and a manually-accessible operating element axially shiftable in the main body and engageable with said latch-engageable element to shift it and said contact ring to position where said latch may engage and retain said latch-engageable element in projected position.

5. In a current-responsive electric circuit controller comprising a main body having two normally electrically-separated terminals one of Which is cylindrical, a bridging contact element movable axially Within said cylindrical terminal and adapted, in one position, to electrically connect said terminals, a spring normally biasing said bridging contact element to inactive position, a latch carried by said main body, a retainer cooperative with said latch and said bridging contact element to hold said bridging contact element in active position, said retainer being oscillable about the axis of the cylindrical terminal, a thermally-responsive electricallyconductive element so associated with said retainer and bridging contact element that upon excessive current iiovv therethrough it Will cause swing of said retainer about its axis to a noncoactive position relative to said retainer, and means, accessible from the exterior of the main body, by which said retainer and bridging contact may be moved respectively to retaining and bridging positions.

6. In a current-responsive electric circuit controller comprising a main body having two normally electrically-separated terminals one of which is cylindrical, a bridging contact element movable axially Within said cylindrical terminal and adapted, in one position, to electrically connect said terminals, a spring normally biasing said bridging contact element to inactive position, a latch carried by said main body, a retainer cooperative with said latch and said bridging contact element to hold said bridging contact element in active position, said retainer being oscillable about the axis of the cylindrical terminal, a thermally-responsive electricallyconductive element so associated with said retainer and bridging contact element that upon excessive current oW therethrough it will cause swing of said retainer about its axis to a noncoactive position relative to said retainer, and means, accessible from the exterior of the main body by which said retainer and bridging contact may be moved respectively to retaining and bridging positions, said means comprising a one- Way connection With said retainer rendered inefective upon excessive current oW through the bridging contact element.

7. A current-responsive electric circuit controller of the character specified in claim 9 wherein the biasing spring and the thermallyresponsive electrically-conductive elements are both helical bimetallic electrically-conductive elements so associated with the retainer as to oppositely rotatively affect said retainer and said biasing means is of substantially greater electrical-conductivity.

FORREST L. HITCHCOCK. 

